The present invention relates to an ear thermometer probe structure and, more particularly, to an ear thermometer probe structure capable of resisting variation of temperature gradient and measuring with high accuracies.
Recently, using ear thermometers to measure the eardrum temperature of infants has become a trend. Because the eardrum is located near the control center of body temperature (i.e., hypophysis) in the skull, and can obtain sufficient supply of blood flow from the carotid, any variation of temperature of the body will be manifested by the eardrum temperature. An ear thermometer utilizes infrared rays to measure heat released by the eardrum so as to obtain the accurate temperature. In addition to measure the true temperature of the body, using an ear thermometer to measure the eardrum temperature can dispense with inconvenience of measuring the anus temperature of infants for the parents, and also has the advantages of quickness, comfort, and convenience.
An ear thermometer usually has a probe structure to be stuck into the ear hole for measuring the eardrum temperature. The ear thermometer probe structure is the main structure affecting the accuracy of measurement. The whole design and assembly stability of the probe directly affect the reliability of an ear thermometer. Especially, stability of the optical path system and influence of thermal conductivity must be taken into account. Because an ear thermometer must be calibrated at a specific temperature when leaving the factory, once the relative positions of the optical path system is changed, transmittance and reflectance efficiency of infrared rays will be directly affected, resulting in erroneous calculation of the ear thermometer. The probe of an ear thermometer thus needs to have a very good vibration-proof capability. Moreover, because the temperature difference of a sensor and the measured object is measured when using infrared rays to measure the temperature, the temperature measured by the sensor will lose its reference value if the temperature of the sensor itself is vulnerable to external temperature in the design of thermal conductivity.
As shown in FIG. 1, a probe structure of a conventional ear thermometer is disclosed in U.S. Pat. No. 5,871,279. A probe 10 comprises a shell body 12 of low thermal conductance. A wave guide 14 is disposed and fixed in the shell body 12. The inner tube wall of the wave guide 14 is plated with gold to enhance reflectance. A filter 16 is disposed at the front end in the wave guide 14. The filter 16 is usually made of material like polypropylene (PP) or polyethylene (PE). Infrared rays are transmitted through the filter 16, are reflected in the wave guide 14, and then reach a sensor (not shown) disposed at the rear end of the wave guide 14. The reflected signal received by the sensor is then quantized into a value for display to obtain the temperature of the human body. In this disclosure, a metal piece 18 is annularly disposed between the rear sections of the shell body 12 and the wave guide 14 to ensure that the filter 16 will not be impacted to influence the optical path system when the probe 10 is impacted. Although this disclosure has a better vibration-proof effect, the disposition of the metal piece 18 lets external heat be more easily conducted to the wave guide 14, hence affecting the temperature of the sensor itself and resulting in incorrect measurement. Furthermore, because the filter 16 is made of material of low strength like PP or PE, once it is pieced by pointed objects to hollow and deform or even be penetrated through, the measured value will be too high notably and thus has no reference value.
As shown in FIG. 2, another probe structure of a conventional ear thermometer is disclosed in U.S. Pat. No. 5,857,775. In a shell body 12 of the probe, a filter 20 is disposed at the foremost end. A sealing pad 22, a collar 24, and a wave guide 14 are disposed behind the filter 20 in order, respectively. The wave guide 14 passes through the hollow regions of the sealing pad 22 and the collar 24 and tightly contacts them. The top end of the wave guide 14 shores up the filter 20. Epoxy 26 is then used to fix all the above components in the shell body 12. In order to accomplish sealing effect, all the components is first place into the shell body 12, and the epoxy 26 is then used to fix all the components in the shell body 12. However, this will increase the difficulty in practical embodiment. Moreover, the wave guide 14 directly presses the filter 20. The sealing pad 22 is neither placed between the filter 20 and the wave guide 14 nor placed between the filter 20 and the shell body 12. Therefore, the sealing pad 22 has a very bad vibration-proof effect. Crack of the filter 20 may easily arise when collision occurs.
In the disclosure of U.S. Pat. No. 6,076,962, the wave guide is omitted, and the sensor is disposed at the foremost end in the shell body of the probe to directly detect heat released by the ear drum so as to reduce error. However, the external environment will directly heat the sensor to let variation of the temperature of the sensor itself be more, and the sensor will be directly and momentarily heated by the ear hole. These two factors will increase variation of temperature gradient to affect the sensor. Therefore, the measured value after comparison of the temperature detected by the sensor with the temperature of the sensor itself is not the real temperature of the human body.
Accordingly, the present invention aims to propose an ear thermometer probe structure having vibration-proof capability and capable of resisting variation of temperature gradient to resolve the problems and drawbacks in the prior art.
The primary object of the present invention is to provide an ear thermometer probe structure, wherein a sensor in the probe structure is located in a sealed air room to reduce the influence of variation of temperature gradient to the sensor. The sensor will thus have a very high temperature stability to effectively enhance the accuracy of measurement.
Another object of the present invention is to provide an ear thermometer probe structure, wherein a filter at the front end in the probe structure is made of silicon chip material with high transmittance of infrared rays to have high strength. Therefore, the probe structure will not be easily pieced through, is airtight and waterproof, can be cleaned with alcohol, and can be used without probe covers.
Another object of the present invention is to provide an ear thermometer probe structure, wherein a sealing pad is disposed at an appropriate position to exactly achieve vibration-proof, water-proof, and dust-proof effects.
According to the present invention, an ear thermometer probe structure comprises a shell body, a hollow thermal absorption component, a wave guide, a filter, an annular sealing pad, and a sensor. The shell body has a narrow front end and a wider rear end to form a probe shape. At least a positioning point is disposed on the inner wall of the shell body. An annular flange is formed at the top of the shell body. The hollow thermal absorption component is disposed in the shell body, and contacts the positioning point of the shell body. An air gap is formed at the part of the hollow thermal absorption component not contacting the shell body. The wave guide is disposed in the hollow portion of the thermal absorption component. The rear section of the wave guide tightly contacts the thermal absorption component, and the front section thereof protrudes out of the thermal absorption component and is separated from the shell body by an air gap. The filter is disposed at the front end of the wave guide. The periphery of the filter contacts the shell body to let infrared rays be transmitted. The annular sealing pad is disposed at the front end in the shell body, and is located between the filter and the annular flange at the top of the shell body. The sensor is disposed behind the wave guide and is fixed on the thermal absorption component. An annular air room is disposed between the sensor and the thermal absorption component and the wave guide.